1. Field of the Invention
The present invention relates to a semiconductor device comprising a circuit including a thin film transistor (hereinafter, referred to as TFT) and a method for manufacturing the semiconductor device. For example, the invention relates to an electronic device on which an electro-optical device as typified by a liquid crystal display panel or a light emitting display device having an organic light emitting element is mounted as a component.
Further, in this specification, the term “semiconductor device” denotes a device in general which can operate by utilizing a semiconductor characteristic. An electro-optical device, a semiconductor circuit, and an electronic device are all included in the semiconductor device.
2. Description of the Related Art
In recent years, technique of forming a thin film transistor (TFT) using a semiconductor thin film (having a thickness of approximately from several to several hundreds nanometers) which is formed over a substrate having an insulating surface has attracted attention. A thin film transistor is broadly applied to electronic devices such as ICs or electro-optical devices, and has been rushed to be developed especially as a switching element of an image display device.
Various applications using such an image display device have been expected, and in particular, application to a portable device attracts attention. A glass substrate or a quartz substrate is widely used now; however, these substrates have some drawbacks such as being fragile and heavy. Further, these substrates are unsuitable for mass-production since it is difficult to use a large-sized glass substrate or a large-sized quartz substrate. Therefore, it has been attempted that a TFT element is formed over a substrate having flexibility as typified by a flexible plastic film.
However, the maximum temperature of the process should be lowered since the heat resistance of a plastic film is low. As a result, it has been impossible to form a TFT having characteristics as favorable as that formed over a glass substrate. Thus, a high-performance liquid crystal display device or a light emitting element using a plastic film has not been realized yet.
Consequently, technique of peeling an element formed over a glass substrate from the substrate and transferring the element to another base material such as a plastic film is proposed.
The applicant proposes peeling or transferring technique disclosed in the following patent document 1 (Patent document 1: Japanese Patent Laid-Open No. H8-288522) or patent document 2 (Patent document 2: Japanese Patent Laid-Open No. H8-250745).
In the case of a very small device such as an IC, a semiconductor wafer is pasted onto an adhesive sheet to be divided as a chip unit, then the divided semiconductor element is picked up from the adhesive sheet, and then the picked up semiconductor element is installed to be mounted in a circuit substrate included in an IC card or the like. Since the semiconductor wafer is used, the semiconductor element has some drawbacks such as being damaged or fragile when being picked up.
It has been recently considered the possibility of utilizing “non contact IC tag” (generally, referred to as non contact data carrier) that can record and read out information out of touch for information management of goods or products, physical distribution management, and the like.
A semiconductor wafer serving as a mother body of a semiconductor chip used for an IC card or a non contact IC tag is expensive and unfit for mass-production.
A the matrix type (multiple patterned type) manufacturing method in which multiple electronic component elements are mounted over a glass substrate and divided into individual pieces to be a product has been distributed. Plural small device are preferably manufactured over a large substrate in consideration for mass-production.
In the case where an integrated circuit including a thin film is formed over a substrate and peeled from the substrate, a fissure (also referred to as crack) may be generated in the integrated circuit in some cases.